Question

State the direction of the incident ray which after reflection from a spherical mirror retraces its path. Give a reason for your answer.

Answer 1

The incident ray which retraces its path after falling on a spherical mirror will be passing through its centre of curvature. The main reason that it doesn't deviate from its path is that it is considered perpendicular to the mirror. Hence the angle of incident will be equal to the angle of reflection which both here zero. This no deviation from the path.